The World Cup's focus on attacking football has won global praise but a cloud scurried across the tournament Tuesday as match fixing claims surrounding Cameroon's participation in the event emerged.

The Cameroon Football Association (Fecafoot) has confirmed it's investigating allegations made in the German media that seven of its players were involved in match fixing during the group stages of the World Cup finals in Brazil.

While previous investigations centered on trying to fix international friendlies or low-profile qualifiers, this is the first time since 1982 that World Cup group stage games have come under scrutiny.

The "Indomitable Lions" were drawn in the same pool as Croatia, Mexico and host nation Brazil, losing all three games.

"We wish to inform the general public that, though not yet contacted by FIFA in regards to this affair, our administration has already instructed its Ethics Committee, to further investigate these accusations," said a Fecafoot statement.

Wilson Raj Perumal, who was detained by police in Finland earlier this year on an international arrest warrant, told Der Spiegel that Cameroon would lose to Croatia while also having a player sent off.

CNN has not been able to independently verify the Der Spiegel report.

Midfielder Alex Song was red carded during the game for lashing out at Croatia striker Mario Mandzukic, while goals from Ivica Olic, Ivan Perisic and a brace from Mandzukic without reply secured a 4-0 victory.

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The match also saw Cameroon players Benoit Assou-Ekotto and Benjamin Moukandjo aggressively confront each other, with television pictures appearing to show Assou-Ekotto attempting to head-butt Moukandjo.

CNN contacted Song's agent although he was not immediately available for comment.

The Fecafoot statement continued: "Recent allegations of fraud around Cameroon 2014 FIFA World Cup three preliminary games, especially Cameroon vs. Croatia, as well of the 'existence of seven bad apples (in our national team)' do not reflect the values and principles promoted by our administration, in line with FIFA Code of Conduct and the ethics of our nation."

In the Der Spiegel interview, Perumal, who CNN is trying to contact, used the expression "seven bad apples."

A FIFA spokesperson told reporters Tuesday that they could not comment on whether an investigation was underway on the manipulation of games.

Fecafoot meanwhile added in its statement that "in 55 years of existence, it has never been sanctioned for, involved in, or even linked to match fixing or any fraud of any kind."

The investigation marks an uncomfortable end to Cameroon's disastrous World Cup campaign.

Players initially refused to board the plane to Brazil until a dispute with Fecafoot over bonus payments was resolved. Although an agreement was eventually reached, the team's departure was delayed by a day.

An opening game 1-0 loss to Mexico was followed up by the 4-0 thrashing by Croatia. Hosts Brazil then completed the misery by defeating the four-time African Cup of Nations champion 4-1.

In the aftermath of the Croatia defeat, coach Volker Finke described the behavior of some of his players as "unacceptable."

"Some players behaved very badly, and that's why we have conceded four goals," Finke said to L'Equipe. "I know that it is difficult to play with 10 men, but that is not a reason to lose it to this point.

"The game was balanced until the red card. The Croatians were more clinical in front of goal, but Cameroon also had chances to score.

"The behavior of some of the players is really not satisfactory. Even when we were 11-a-side, it was not acceptable."

In 1982, Algeria, despite having beaten then West Germany, went out after a seemingly contrived 1-0 win over Austria.